1. Field of the Invention
The present invention relates to a pump.
2. Background Information
Pumps are used to create fluid flow and increase a fluid pressure within an hydraulic system. For example, some internal combustion engines contain a pump that increases the pressure of hydraulic fluid which is used to hydraulically actuate intensified fuel injectors of the engine. Such engine pumps may contain one or more pistons that are reciprocated within a pump chamber by a wobble plate. Each revolution of the wobble plate causes the piston to draw in fluid through an inlet port and then pressurize and push the fluid through an outlet port of the pump.
The wobble plate is mechanically coupled to the rotational output of the engine. The speed of the pump is controlled by the speed of the engine. Consequently, the output of the pump increases with a corresponding increase in the engine speed. It may be desirable to increase or decrease the output of the pump without varying the speed of the engine. It would therefore be desirable to provide a pump which can vary the pump output to a number of different levels for a given input speed of the pump.